The evolving landscape of head and neck brachytherapy: A scoping review

Purpose:
Since the last update of GEC-ESTRO (Groupe Européen de Curiethérapie – European Society for Therapeutic Radiology and Oncology) recommendations for head and neck (HN) brachytherapy in 2017, advances in understanding and management of HN cancers have influenced brachytherapy. We conducted a scoping review to depict the evolution of HN brachytherapy research and practice, and identify emerging topics since the previously published guidelines.

Material and methods:
Systematic literature search was performed in PubMed, EBSCOhost, Europe PMC, and Google Scholar databases for articles on HN brachytherapy from 2017 onwards; the search was last done on June 29, 2023. We included primary studies on HN brachytherapy in English, complemented by bibliography scanning of secondary studies. Iterative team approach was employed in data extraction and charting. Quantitative and qualitative analyses and narrative synthesis were performed.

Results:
Systematic search yielded 215 unique articles. A total of 132 primary studies were included: 112 on clinical outcomes (retrospective cohorts in majority, n = 72), and 22 were simulation and dosimetric studies. China consistently produced the most research output per year. The most studied sites were the oral cavity (n = 84), oropharynx (n = 37), and salivary glands (n = 20). While most reported on high-dose-rate brachytherapy (n = 57), there was resurgence of studies on low-dose-rate (LDR) brachytherapy (n = 50) in the form of permanent seed implants. In the latter, CT (n = 50) and template (n = 27) guidance were described. While majority discussed definitive brachytherapy, 18 reported on perioperative brachytherapy. Several reported on 3D printing for template and applicator design (n = 11) as well as new approaches to dose calculation or dose optimization algorithms (n = 2).

Conclusions:
The current scoping review identified recent trends in HN brachytherapy, such as application in other HN sites, use of LDR seed implants, perioperative brachytherapy, and 3D printing in template design. Data from these recent publications provide a foundation for further investigations, which can generate evidence for succeeding guidelines.